Unreasonable Errors on PHP Slim 3 Middleware
Asked Answered
L

8

6

I am trying to use the ValidationErrorsMiddleware.php class as a middleware, so I added the following code to my bootstrap/app.php:

$app->add(new App\Middleware\ValidationErrorsMiddleware($container));

I got the following errors after the above code is added to my app.php:

Fatal error: Uncaught exception 'RuntimeException' with message 'Unexpected data in output buffer. Maybe you have characters before an opening <?php tag?' in C:\wamp64\www\authentication\vendor\slim\slim\Slim\App.php on line 552
RuntimeException: Unexpected data in output buffer. Maybe you have characters before an opening <?php tag? in C:\wamp64\www\authentication\vendor\slim\slim\Slim\App.php on line 552

Just in case, anyone needs to look at the code of my classes and app.php, I have included them down here


ValidationErrorsMiddleware.php

<?php

namespace App\Middleware;

class ValidationErrorsMiddleware extends Middleware {

  public function __invoke($request, $response, $next) {

    var_dump('middleware');
    $response = $next($request, $response);

    return $response;
  }
}

Middleware.php

<?php

namespace App\Middleware;

class Middleware {

protected $container;

  public function __construct($container) {

    $this->container = $container;
  }
}

App.php

<?php

session_start();

require __DIR__ . '/../vendor/autoload.php';

$app = new \Slim\App([
'settings' => [
    'determineRouteBeforeAppMiddleware' => false,
    'displayErrorDetails' => true,
    'db' => [
        // Eloquent configuration
        'driver' => 'mysql',
        'host' => 'localhost',
        'database' => 'phpdb',
        'username' => 'root',
        'password' => 'root',
        'charset' => 'utf8',
        'collation' => 'utf8_unicode_ci',
        'prefix' => '',
    ]
],
]);


$container = $app->getContainer();

$app->add(new App\Middleware\ValidationErrorsMiddleware($container));

require __DIR__ . '/../app/routes.php';
Limpkin answered 18/5, 2016 at 7:46 Comment(1)
The same problem starts to happen with me since I've run composer again. I am using "slim/slim": "^3.0" ... I've compared the code of App.php and found a new code that throws this exception, but I did not understand the cause of that.Amelioration
A
14

I've fixed my problem doing this:

return [
'settings' => [
    // Slim Settings
    'determineRouteBeforeAppMiddleware' => true,
    'displayErrorDetails' => true,
    'addContentLengthHeader' => false,

I added the attribute addContentLengthHeader with the value false in the settings array.

But I still did not understand what this is for

UPDATE

This problem happens because of the line var_dump(middleware) thats changes the content length of the response. My solution was just a hack. Thanks to @iKlsR for the right answer.

Amelioration answered 18/5, 2016 at 15:22 Comment(4)
Awesome!! It really works :)) I had been struggling with the problem for a day, and now I can continue working on the authentication things. Thanks.Limpkin
I think i might have a good guess about the addContentLengthHeader: I had the same issue, and when i turned off, the output showed with the extra PHP E_NOTICE which was html formatted. So my guess is that Slim counts the expected length, and before output it compares it to the actual length, and the error got in there some other way - so the two length mismatched and that caused an exception.Maritsa
You should change the accepted answer to iKlsR's answer, since yours is a 'hack' and not a true solution ;) No offenseMaritsa
@MarcioBarroso this is not up to you, it's the asker who does this, no worries all the answers are visible, I wouldn't say your approach was a hack but it can have some adverse effects down the line. It's good to know what the configuration options do instead of just blindly turning them off to skip an error.Sequoia
S
6

Setting addContentLengthHeader to false is not a proper fix and can lead to woes later on when your app gets larger. Your problem is the var_dump('middleware'); which you are printing before you return the response. This makes the size of your Content-Length header incorrect, thus the error, since there are characters outside of this. php should also hint at this by letting you know something about unexpected data if you have error reporting on.

To test or modify your middleware with statements, edit the response body with $response->getBody()->write('message'); tho a simple die('message'); should be good enough to see if it was hit.

Sequoia answered 22/6, 2016 at 16:6 Comment(1)
the code in this question is follow youtube.com/…. Can you explain why in this video, they don't get the error with header but me and the OP gotEgyptian
C
1

I had the same problem because I called the $app->run(); statement twice. I just deleted one of them and everything worked well (keeping: addContentLengthHeader as true).

Cwmbran answered 31/5, 2017 at 14:26 Comment(1)
This is the solution I've searched hours for, didn't even realize I had multiple $app->run();'sFalk
W
0

I had the same issue with the given tutorial, the Fatal error is produced by this line:

$this->container->view->getEnvironment()->addGlobal('errors', $_SESSION['errors']);
unset($_SESSION['errors']);

the $_SESSION['errors'] on boot is not set and in this case we receive a Notice which causes a Fatal Error

what I made, I check on boot if $_SESSION['errors'] is set

if(isset($_SESSION['errors'])) {
        $this->container->view->getEnvironment()->addGlobal('errors', $_SESSION['errors']);
    }

    unset($_SESSION['errors']);
Wadleigh answered 12/4, 2017 at 7:33 Comment(0)
F
0

Its actually a buffer problem related to buffering either turn off the buffer by going into the "php.ini" file or simply use ob_end_clean() at the beginning of your script...

Fortson answered 7/9, 2017 at 5:56 Comment(0)
C
0

In my case I had a double $app->run(); code.

Carpo answered 17/6, 2019 at 9:57 Comment(0)
C
0

If for someone all the solutions above didn't work, you will need to check out if any of the files you're including is not coded as UTF8-Bom (or whatever-format-Bom), this answer here help to fix the problem, and can be done through vscode too if you select the correct format

Characteristic answered 13/9, 2019 at 19:54 Comment(0)
D
0

only you've edit the next in your index:

$app = new \Slim\App([
    'settings' => [
        'addContentLengthHeader' => false
    ]
]);
Dionedionis answered 26/9, 2019 at 18:46 Comment(0)

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